Comparison of the antihypertensive efficacy of felodipine and hydrochlorothiazide in essential hypertension with patients insufficiently controlled by beta-blocker treatment alone

This double-blind controlled study was designed to evaluate the antihypertensive efficacy and tolerability of felodipine and hydrochlorothiazide (HCT) in patients with essential hypertension whose blood pressure had not been normalized by beta-blocker monotherapy. After a run-in period with metoprolol 200-mg slow-release formulation (MR 200), 77 patients with arterial hypertension at World Health Organization stages 1-3, whose blood pressure was insufficiently controlled by full doses of the beta-blocker, were randomized into two groups: MR200 plus felodipine 5 mg BID or MR 200 plus HCT 25 mg once daily for four weeks. At the end of this period, the doses of felodipine or HCT were doubled for a further four weeks if measured blood pressures warranted an increase. Results showed no significant difference in the antihypertensive efficacy of either felodipine or HCT, in association with the beta-blocker used. The double-dose phase was entered by 28.9% of HCT patients, compared with 14.7% of felodipine patients. There was a slight tendency for heart rate to rise with felodipine (+5.2%) and to fall with HCT (-1.2%). Five patients on felodipine and one on HCT were withdrawn from the study because of side effects, all of which were resolved by suspending treatment. Both drugs had a similar number of minor side effects. Main laboratory tests revealed a tendency toward hypokalemia in HCT patients, together with an increase in plasma creatinine levels and uricemia, which did not reach statistical significance. In association with a beta-blocker, both felodipine and HCT appear to have similar antihypertensive effects in patients insufficiently controlled by beta-blocker monotherapy.